This invention relates to a circuit for the reduction of ripple and intermodulation products on a common a.c. or d.c. supply line by the synchronization of switched mode power supplies. Switched power supplies are commonly used in electronic equipment and can result in serious interference problems being produced on the electric lines providing power to the equipment. Electromagnetic interference filters are used to reduce the generated interference to acceptable levels as determined by Government regulations or the sensitivity of other equipment proximate to the generated interference. Reduction of the ripple current in the power lines by this invention reduces the demands placed upon the interference filters and results in a cost effective technique for interference reduction.